1. Field of the Invention
The present invention relates to a signal processing apparatus and method, a recording medium, and a program. Particularly, the present invention relates to a signal processing apparatus and method capable of audio scene-change detection, a recording medium, and a program.
2. Description of the Related Art
In audio/video signals obtained from television broadcasts, radio broadcasts, video tape, video disk, or the like, points (scene changes) accompanied by a change of context or scene in the content are used for editing, indexing, searching, or summarizing such audio/video signals.
For example, scene-change detection is performed by detecting a shot cut accompanied by a large change in the video signal, i.e., a cut change, and by using the cut change as the scene change. However, there may sometimes be a plurality of cut changes in the same scene, thus causing more scene changes than necessary to be detected in such a scene-change detection method.
An approach disclosed in Japanese Unexamined Patent Application Publication No. 5-37893 is to record and play back the outline of a television signal by detecting the difference between frames of the video signal, and by sequentially recording and playing back still pictures at that time.
Japanese Unexamined Patent Application Publication No. 2000-5111743 discloses a method in which the minimum level of an audio signal in a certain interval is identified as a background audio level and a point accompanied by a large change in the background audio level is identified as a scene change.
In this method, however, scene changes may not be accurately detected because background audio and audio other than the background audio may not be clearly distinguished from each other, a scene change may not necessarily be accompanied by a change in the background audio level, there may be a change of background audio level in the same scene, etc.
Another possible method is to detect a silent interval as the scene change; however, there may be an abrupt change in the audio signal without any silent interval being inserted. Thus, scene changes may not be accurately detected in this method.
Therefore, there has been a problem in that scene changes may not be accurately detected.